Bieber wrote: "Love the way you look at me" and posted a romantic photo of the two where Gomez has her arms draped around him with a smile on her face.
The news comes on the heels of Gomez canceling her "Stars Dance" tour, citing she needed "me time."
Speculation began last Thursday when the couple was spotted together near Bieber’s home in Calabasas, CA. Bieber and Gomez broke up in 2012.
According to the website, Bieber recently revealed he still has feelings for Gomez during an appearance on Big Boy’s radio show, on Power 106.
"I wrote the best music once my heart was broken," he said. "‘All That Matters' was written when I was in a great place in my relationship, and at that time, she was all that mattered in my life."
Bieber continued, "[The break up] affected us, especially when we are in front of so many people. It's such a public thing. It's just hard for the both of us. But you know, she's a great woman. I love her till this day."
Reps for Bieber and Gomez have not commented on the status of the relationship.